Nonheme Iron Electron-Transfer Proteins

Malkin, Richard; Rabinowitz, Jesse C.

doi:10.1146/annurev.bi.36.070167.000553

Cited by 95 publications

(35 citation statements)

References 35 publications

(80 reference statements)

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“…The inhibition produced by p-chloromercuribenzoate or Hg2+ may be a result of a combination with the imidazole groups of a protein of the electrontransport chain (cf. Webb, 1966), but it is possible that some sulphur-containing groups of a special type exist in the microsomes and it is highly significant that a similar pattern of reactivity to thiol reagents is found in the bacterial and plant ferredoxins (Malkin & Rabinowitz, 1967). These observations, coupled with those on the role of iron in the system (Wills, 1969a), may be reasonably interpreted on the basis that a ferredoxin-type protein forms an essential part of the NADPH system catalysing lipid peroxide formation.…”

Section: Discussionmentioning

confidence: 99%

Lipid peroxide formation in microsomes. General considerations

Wills

1969

Biochemical Journal

529

128

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1. Liver microsomes form lipid peroxide when incubated with ascorbate or NADPH, but not with NADH. Increasing the concentration of ascorbate beyond the optimum (05mM) decreases the rate of lipid peroxide formation, but this effect does not occur with NADPH. Other reducing agents such as p-phenylenediamine or ferricyanide were not able to replace ascorbate and induce lipid peroxide formation. 2. The rate of ascorbate-induced peroxidation is optimum at pH 6-0 whereas the rate of the NADPH system is optimum at pH7-0. Both systems require phosphate for maximum activity. 3. Lipid peroxide formation occurs at the maximum specific rate in very dilute microsome suspensions (0-15mg. of protein/ ml.). 4. Treatment of microsomes with deoxycholate and other detergents causes membrane disintegration and inhibits lipid peroxide formation. 5. Lipid peroxide formation is accompanied by a rapid uptake of oxygen and there is a large excess of oxygen utilized for each molecule of malonaldehyde measured in the peroxide method. 6. Boiled microsomes form lipid peroxide in the presence of ascorbate, but not if NADPH is added. 7. Lipid peroxide formation induced by NADPH is strongly inhibited by p-chloromercuribenzoate, weakly inhibited by N-ethylmaleimide and unaffected by iodoacetamide. Ascorbate-induced peroxidation in untreated microsomes is unaffected by p-chloromercuribenzoate, but inhibited if boiled microsomes are used. These experiments may be interpreted on the basis that a ferredoxin-type protein forms part of the system in which NADPH induces lipid peroxide formation. 8. Most heavy-metal ions, with the exception of inorganic iron (Fe2+ or Fes+), which activates, inhibit both ascorbate-induced and NADPHinduced peroxidation. Mg2+ increases the rate ofperoxidation whereas Ca2+ inhibits it. 9. Lipid peroxide formation is inhibited strongly by GSH and weakly by cysteine. Ascorbate-induced peroxidation is much more sensitive than NADPH-induced peroxidation. 10. Peroxidation is strongly inhibited by addition of low concentrations (O-01-0-1 Mr) of cytocbrome c or ofhaemoglobin. 11. It is considered that lipid peroxide formation occurs as a result of the operation of the microsomal electrontransport chain switching from hydroxylation to oxidize unsaturated lipids of the endoplasmic reticulum.

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Section: Discussionmentioning

confidence: 99%

Lipid peroxide formation in microsomes. General considerations

Wills

1969

Biochemical Journal

529

128

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“…of he.avy metals, d.i,fficult ( 22). The importance .of ,and interest in, the s.tudy ,of these non-heme' iron proteins is illustrated by the special Symposia on these pro.teins held in Hawaii (Honolulu,19,63) and in Ye,llow Spri~gs (Ohio, 1965).…”

Section: + 2atp + 02mentioning

confidence: 99%

“…Conflicti!1g reports have appeared in the literature r~gardi!1g the sulfhydryl content pf the plant (62,27,32) and bacterial . ( 22,89,25 3) Palmer.etal. (96) (41); no correction applied.…”

Section: Determination Of Total Nitrogenmentioning

confidence: 99%

Isolation and characterization of taro ferredoxin

Rao

1969

Phytochemistry

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“…This latter protein has a molecular weight of 6000 and contains 8 iron atoms, 8 moles of cysteine, and 6-8 moles of acid labile sulfur. [7] The cytochrome c spectrum is similar to that of hemoglobin but shows a higher sulfur content. It also contains so=.…”

Section: Methodsmentioning

confidence: 85%

Estimation of Protein Quantity and Quality by X-Ray Photoelectron Spectroscopy.

Klein¹,

Kramer²

1970

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Nonheme Iron Electron-Transfer Proteins

Cited by 95 publications

References 35 publications

Lipid peroxide formation in microsomes. General considerations

Lipid peroxide formation in microsomes. General considerations

Isolation and characterization of taro ferredoxin

Estimation of Protein Quantity and Quality by X-Ray Photoelectron Spectroscopy.

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